1. Field of the Invention
The invention relates to a breaking and/or drilling hammer with a handle which is resiliently biased with respect to the hammer casing.
2. Description of the Related Art
The previously known resiliently biased systems for reducing the vibration transmitted to the hand and arm are configured such that an angular offset between the device and the handle is prevented, or the longitudinal springing in the direction of action of the tool and the lateral springing are designed to be approximately equal and rather hard, with the result that the damping of the vibration leaves something to be desired.
In addition, fixed springing having an invariant spring characteristic and a relatively short spring travel has proven to be disadvantageous, since it does not allow adaptation to different operating conditions, such as, in particular, the type of material to be worked.
GB-A-565,783 discloses a hammer with a handle which is resiliently biased on all sides with respect to a hammer casing in a manner such that it can move to a limited extent, and which can be displaced to a limited extent with respect to the hammer casing along two rectilinear guides. Each of the rectilinear guides has a guide rod and a guide sleeve, between which a rubber element is arranged for the purpose of springing, this rubber element being loaded in shear when the hammer is operated. Because of the shear forces, there is the risk that the connection between the handle and the hammer casing will become detached. Because of the slight guiding action of the rectilinear guides, the hammer is, moreover, difficult to handle.
Another vibration-insulating handle connection design is disclosed by DE-A-39 13 971, but this was developed for hand-held abrasive disk grinders and is not suitable for use in hammers in which primarily high forces act in the longitudinal direction of the hammer.
Further examples of vibration-damped handles will be found in U.S. Pat. No. 4,401,167 and EP-A-0 066 779.